Mosi heating element is a kind of resistance heating element basically made of pure molybdenum Disilicide, it is a High-Density Material. It forms a dense quartz ceramic protective layer on the surface at high temperature to protect itself from oxidation, and has strong oxidation resistance.
The protective layer of Mosi2 has a strong regenerative ability under oxidative environment and high temperature conditions, Despite molydisilicide heating elementsrobust appearance they are a fragile, glasslike material with low mechanical shock resistance.
In oxidizing atmosphere, Mosi2 Heating Element’s Max temperature can reach 1900 ℃ (3452℉) and its applicable temperature is 500℃-1850℃ (932℉ – 3362 ℉).
Basically, The maximum element temperature is always 100 °C (212℉) higher than the maximum rated furnace temperature, so for example we use 1800 °C (3272℉) elements in our 1700 °C (3092℉) furnaces.
Straight Mosi2 heating elements are the most common shape and are used in various applications, including ceramics, metallurgy, and heat treatment. They are available in different diameters and lengths, depending on the requirements of the application.
U-shaped Mosi2 heating elements are designed for applications where a uniform heat distribution is required. The U shape allows for a larger heating surface area, which helps to distribute heat evenly throughout the furnace. The element consists of two cold ends (Lu) and a U-shaped hot section (Le). The cold ends are twice the diameter of the hot section and are attached by a weld.
U-Shaped is commonly used in the production of glass, ceramics, and metallurgy.
W-shaped Mosi2 heating elements are designed for high-temperature applications where a high degree of thermal shock resistance is required. The unique W shape allows the element to expand and contract more freely, which reduces the likelihood of cracking or breaking due to thermal stress.
W-Shaped is commonly used in the semiconductor industry and other high-temperature applications.
L-shaped Mosi2 heating elements are used in applications where space is limited or where a specific heating pattern is required. The L shape allows the element to be positioned in a way that maximizes its heating efficiency while minimizing its footprint.
L-shaped is commonly used in the production of ceramics, glass, and metallurgy.
Double spiral Mosi2 heating elements are designed for applications where a higher degree of heating efficiency is required. The double spiral design allows for a larger heating surface area, which increases the element’s overall heating capacity.
Double Spiral is commonly used in the production of semiconductors, electronic components, and other high-temperature applications.
Note: For more details, please see this article： https://sicelement.com/different-shapes-of-mosi2-heating-elements/
The MoSi2 heating element has a long, thin, tubular shape with two terminals. The body of the heating element is composed of a dense ceramic material, which is made of high-purity MoSi2 sintered at high temperatures and has a high melting point and good oxidation resistance.
The molybdenum core is coated with quartz glass. The elements become nearly liquid as they approach the maximum temperature, and the glass surface reacts with the oxygen in the air atmosphere to form a renewed coating of protective glass on the element surface.
The two terminals of the heating element are made of metallic materials such as nickel-chromium alloy (NiCr) or tungsten-rhenium alloy (Re). These materials have good electrical conductivity and thermal stability and can efficiently transfer electrical energy into thermal energy.
Mosi2 heating elements work based on the principle of electrical resistance heating. When an electric current is passed through the Mosi2 heating element, it produces heat due to the resistance of the material.
The heat generated by the Mosi2 heating element is proportional to the amount of electric current passed through it, which allows for precise temperature control.
Mosi2 heating elements have good stability and mechanical strength at high temperatures, and can maintain long-term stable performance at high temperatures. In addition, Mosi2 heating elements also have excellent oxidation resistance and corrosion resistance, so they have a long service life when used at high temperatures.
Mosi2 heating elements are relatively expensive and have high costs, and they are also susceptible to mechanical shock or thermal shock, which can lead to problems such as breakage.
Mosi2 heating elements have a higher operating temperature, longer service life and better stability than resistance wire heating elements. The resistance wire heating element is relatively cheap, but it is easy to be damaged due to overload, and it is prone to problems such as oxidation and fracture at high temperature.
Both Mosi2 heating elements and silicon carbide heating elements have stability and mechanical strength at high temperatures, but Mosi2 heating elements have better oxidation and corrosion resistance than silicon carbide heating elements, so they last longer at high temperatures. However, the price of Mosi2 heating elements is relatively high, while the cost of SiC heating elements is relatively low.
Mosi2 heating element can be widely used in such applications as sintering and heat treatment of ceramics, magnet, glass, metallurgy, refractory etc. Especially, Mosi2 heater is the requisite heating element in heat sintering process of high-performance ceramics, high rank synthetic crystalloid, sophisticated structure cermets, glass fiber, optical fiber as well as high rank alloy steel, and it is the best environment-protecting product in the heating area in the 21st Century.
Below we mainly explain the application of heating elements in industry and the application in laboratory and research
Mosi2 heating elements are widely used in various industries such as metallurgy, glass, ceramic, and semiconductor manufacturing due to their high-temperature stability, long service life, and excellent oxidation resistance. They are used in high-temperature furnaces, kilns, and ovens for processes such as sintering, heat treatment, annealing, and melting.
Mosi2 heating elements are also used in laboratory and research settings for high-temperature experiments and testing. They are used in high-temperature furnaces and ovens for processes such as crystal growth, material synthesis, and thermal analysis. Mosi2 heating elements are preferred for their stability and uniformity of heating, which is crucial in many research applications.
Maximum Element Temperature: 1700 °C (3092℉)
Most types of industrial furnaces for heat treating, forging, sintering, glass melting and refining, and for use in radiant tubes.
Maximum Element Temperature: 1800 °C (3272℉)
Laboratory furnaces, testing equipment, and high temperature sintering production furnaces.
Laboratory furnaces, testing equipment, and high temperature sintering production furnaces up to 1800 °C (3272 °F)furnace temperature.
Oxygen-resistance under high temperature: in oxidizing atmosphere, a layer of compact quartz (SiO2)protective film is formed on the surface of element owing to the high-temperature combustion, which prevent Mosi2 from continuously oxidizing.
When the element temperature is higher than 1700 °C (3092 °F), the sio2 protective film will be fused because its fusing point is 1710 ℃ (3110℉) and the sio2 is fused into molten dropa owing to the action of its surface extension, which cause losing its protective ability. In the oxidizing atmosphere, when the element is continuously used, the protective film forms again.
The MoSi2 heating element must not be used in the temperature between 400 °C (752 °F)and 700 °C (1292 °F) for a long time, otherwise the element will be cremated under the strong oxidizing function in the low temperature.
According to the structure, the temperature and atmosphere in the correct choice of components surface load is the key element to the highest life, based on the thermal radiation components uncrossed circumstance temperature, temperature and surface load components, the shaded part for common surface load — the temperature range.
| Furnace Temp(°C) | 1400 | 1500 | 1600 | 1650 | 1700 |
| Surface load of hot zone(w/cm²) | <18 | <15 | <12 | <10 | <8 |
The Moly-D elements are low-voltage high-current elements. Below is the maximum recommended current for each standard hot zone diameter. The hot zones can take more power but the cold ends tend to over heat and cause strap and clamp failure.
| Hot Zone Diameter in mm | 3 | 4 | 6 | 9 | 12 |
| Current Amperes | 75 | 115 | 200 | 365 | 560 |
The resistivity of element rapidly rises along with the temperature rises, under normal operating condition, generally the element resistance doesn’t change with the application time changing. So the old and new elements can be used together.
The mosi2 heating element is a resistant type heater that converts electrical energy to heat energy according to Joules Law W=I2R. W = Power in watts, I = Current in amperes, R = Resistance in ohms.
Molybdenum disilicide increases in resistance by a actor of approximately 10 between 20 °C (68℉) and 1800 °C (3272 °F). Therefore the hot zone temperature must be known before the resistance of the hot zone can be determined.
The mosi2 element is a high temperature element that performs well and gives long service life at its rated temperature of 1710 °C (3110 °F) or 1800 °C (3272 °F). Therefore, we recommend designing to element temperatures of 1675 ºC (3047℉) for the grade 1700 Grade and 1775 °C (3227℉) for the grade 1800.
The resistance values for 1mm of length for standard element diameters at 1675 °C (3047 °F) and 1775 °C (3227 °F) are shown on the following Table.
| Hot | Resistance in ohms per mm of length 1675℃ and 1775℃ | |
| Section Diameter | 1675℃ (3047 °F) | 1775℃ (3227 °F) |
| 3 | 0. 00493 | 0. 000523 |
| 4 | 0. 000277 | 0. 000294 |
| 6 | 0. 000123 | 0. 000131 |
| 9 | 0. 000054 | 0. 000058 |
| 12 | 0. 00003 | 0. 000032 |
| Atmosphere | 1700 | 1800 | 1850 | 1900 |
| Air | 1700 | 1800 | 1830 | 1850 |
| Nitrogen | 1600 | 1700 | 1700 | 1700 |
| Ar Ne Argon, Helium | 1600 | 1700 | 1700 | 1700 |
| Dry Hydrogen (dew point)-80℃ (176℉) | 1150 | 1150 | 1150 | 1150 |
| Wet Hydrogen (dew point)-20℃ (68℉) | 1450 | 1450 | 1450 | 1450 |
| Exogas(e. g. 10% CO2, 50% CO, 15%H2) | 1600 | 1700 | 1700 | 1700 |
| Exogas(e. g. 40% CO2, 20% CO) | 1400 | 1450 | 1450 | 1450 |
| Cracked and partially burnt ammonia（8%H2) | 1400 | 1450 | 1450 | 1450 |
When the elements are new (first used) they must be brought to an element temperature of 1200 °C (2192°F) or higher quickly in air. If operated at a surface temperature in the 500 °C (932 °F) to 700 °C (1292 °F) range for any length of time before the glaze is formed the elements will be destroyed.
After the glaze is formed, the element may be operated at low temperatures as long as the glaze is intact.
To avoid high current surges which may cause damage to MoSi2 heating elements, the recommend starting procedure as following:
| Small Furnace(Power 100KW) | Big Furnace(Power100KW-500KW) | ||
| Furnace Temperature °C | Voltage | Furnace Temperature °C | Voltage |
| 20-150 | 1/3 | 20-300 | 1/3 |
| 150-500 | 2/3 | 300-700 | 2/3 |
| 500-Working Temperature | Full | 700-working Temperature | Full |
| Note: Shifting gear must be done quickly, otherwise high current surges may cause damage. | |||
Read more:
How to calculate the power on a U-shapes mosi2 heating element?
Can MoSi2 Replace SiC Heating Elements?
Mosi2 Heating Elements Installation and Maintenance
a. CHOOSE THE RIGHT SIZE AND SHAPE: Choosing the right size and shape is very important when selecting a Mosi2 heating element. Factors to consider include the size of the heating chamber or furnace, the required temperature of the furnace, and even heat distribution.
b. Pay attention to the rated power and voltage of the heating element: The rated power and voltage of the Mosi2 heating element should also match the furnace to ensure compatibility with the power supply and control system. Overloading a heating element can cause it to fail prematurely, while undersizing a heating element can lead to insufficient heating.
c. Choosing the right heating controller: Choosing the right controller is also very important for the efficient operation of the Mosi2 heating elements. Choosing the correct controller depends on the temperature range required, the rate of heating, and the level of precision and control required.
Sunshine is a supplier and manufacturer with many years of experience in producing heating elements, long life and efficient heating are our specialties.
We sell Mosi2 components at reasonable prices, and provide perfect after-sales service and technical guidance.
For bulkbuy, please contact us, you will get a satisfactory price.
